1. Field of the Invention
The present invention relates to an improvement in wire winding method and wire winding apparatus for winding a wire on a plurality of poles provided along an outer periphery of a stator core.
2. Description of the Prior Art
A method and an apparatus for winding a wire on each pole of a stator core have already been disclosed in Japanese Patent Laid-Open No. 10-112962, for example.
In the above-described conventional method and apparatus, a wire is wound on a pole as an object the wire is to be wound, by revolving a wire support that supports an intermediate portion of a tense wire while allowing the wire to run. In this case, when a thick wire with a diameter exceeding 1.1 mmØ is wound, it is difficult to wind the wire because bend marks remain on the wire. If the wire tension is set large to prevent the wire from getting bend marks, the wire is damaged undesirably.
The cause for such a phenomenon will be explained with reference to FIGS. 5 and 6. The wire support revolves around a revolution centerline C, which passes through the center of a pole P on which the wire is to be wound and is perpendicular to the axis of a stator core 11, so as to draw a circular path T indicated by a chain line. In this case, the length of a wire 13 from a contact point of the wire 13 with the pole P to the wire support varies because the pole P has a rectangular longitudinal cross section that is long in the axial direction of the stator core 11. Specifically, the wire length from the contact point of the wire 13 with the pole P to the wire support (circular path T) varies as follows: Taking the wire length when the wire support is positioned at point PA between both side formers 14A and 14B as, for example, xe2x80x9c1xe2x80x9d, the wire length when the wire support is positioned at point PB at which the wire 13 starts to come into contact with one side former 14A increases to, for example, xe2x80x9c1.04xe2x80x9d, the wire length when the wire support is positioned at point PC at which the wire 13 is in contact with one side former 14A further increases to, for example, xe2x80x9c1.27xe2x80x9d, and the wire length when the wire support is positioned at point PD at which the wire 13 separates from one side former 14A decreases to, for example, xe2x80x9c1.26xe2x80x9d. Although the wire length at point PC from the contact point of the wire 13 with the pole P to the wire support (circular path T) is, for example, xe2x80x9c1.12xe2x80x9d in terms of straight distance, the length of the wire 13 at point PC is xe2x80x9c1.27xe2x80x9d, which is longer than xe2x80x9c1.12xe2x80x9d, as described above because the wire 13 is in contact with the side former 14A as shown in FIG. 6.
Thus, the wire length from the contact point of the wire 13 with the pole P to the wire support (circular path T) in the range WA in which the wire support travels from point PB to point PD to wind the wire 13 on one end face along the lengthwise direction of the pole P (axial direction of the stator core 11), that is, in the range in which the wire 13 passes on each of the side formers 14A and 14B is larger than the wire length from the contact point of the wire 13 with the pole P to the wire support (circular path T) in the range WB in which the wire support passes through point PA after separating from the side former 14A and travels to point PB to wind the wire 13 on one side face along the width direction of the pole P (direction perpendicular to the axis of the stator core 11), that is, in the range from the point where the wire 13 has passed on one of the side formers 14A and 14B to the point where the wire 13 starts to come into contact the other thereof, so that the tension acting on the wire 13 in the ranges WA, WA is higher than the tension acting on the wire 13 in the ranges WB, WB. Therefore, during the time when the wire support travels from point PA to point PD, the wire 13 starts to strongly come into contact with the side former 14A, 14B at point PB, and passes through point PC while being bent. Subsequently, the tension adversely decreases at point PD, so that the wire 13 undesirably gets a bend mark.
The present invention has been achieved in view of the above situation, and accordingly an object thereof is to provide a winding method and a winding apparatus for a stator core, in which even a relatively thick wire can be wound while being prevented from getting bend marks, whereby the quality as a stator can be improved.
To attain the above object, according to a first feature of the present invention, there is provided a wire winding method for a stator core in which, in order to wind a wire on a plurality of poles having a rectangular longitudinal cross section that is long in an axial direction of said stator core, a pair of side formers for guiding the wire into slots on opposite sides of a pole on which said wire is to be wound among said plural poles are disposed on an outside of said stator core, and in this state, a wire support which supports an intermediate portion of the wire fed from a wire feeding means while allowing the wire to run and which can feed the wire in response to an action of a tension of a predetermined value or higher is revolved so as to draw a circular path around a revolution centerline which passes through the center of the pole on which the wire is to be wound, the revolution centerline being perpendicular to the axis of said stator core, the method comprising setting the tension acting on the wire during the time when the wire between the pole on which the wire is to be wound and said wire support passes on each of said side formers to be lower than the tension acting on the wire from the time when the wire between the pole on which the wire is to be wound and said wire support has passed on one of said side formers to the time when the wire starts to come into contact with the other thereof.
According to the first feature, the tension acting on the wire when the wire passes on the side formers is made relatively low, and the tension is made relatively high immediately after the wire has passed on the side former, so that even if the wire is relatively thick, the bent portion of the wire can be wound so as to adjust itself to the pole while preventing the wire from getting a bend mark at the portion bent by the side former to the utmost. Therefore, even a relatively thick wire can be wound while being prevented from getting bend marks, and also damage to the wire can be avoided, so that the quality as a stator can be improved.
Also, according to a second feature of the present invention, there is provided a wire winding apparatus for a stator core, comprising: a pair of side formers disposed on an outside of said stator core to guide a wire into slots on opposite sides of a pole on which the wire is to be wound among a plurality of poles having a rectangular longitudinal cross section that is long in the axial direction of said stator core; a wire feeding means disposed on the outside of said stator core so as to enable the feed of the wire in response to an action of a tension of a predetermined value or higher; a flier provided to be rotatable around a revolution centerline passing through the center of the pole on which the wire is to be wound, the revolution centerline being perpendicular to the axis of said stator core, the flier having a wire support supporting an intermediate portion of the wire fed from said wire feeding means while allowing the wire to run and being provided at a position displaced from said revolution centerline; and a rotation driving means which rotates to drive said flier, wherein said winding apparatus further comprises: a movable pulley around which the wire is set at a position between said flier and said wire feeding means so that the tension of the wire is adjustable; and a movable pulley driving means provided between said rotation driving means and said movable pulley so as to move said movable pulley to a position at which the tension acting on the wire during the time when the wire between the pole on which the wire is to be wound and said wire support passes on each of said side formers is lower than the tension acting on the wire from the time when the wire between the pole on which the wire is to be wound and said wire support has passed on one of said side formers to the time when the wire starts to come into contact with the other thereof.
According to the second feature, the movable pulley is moved in association with the rotation of the flier that is rotated by the rotation driving means, whereby the tension acting on the wire when the wire passes on each of the side formers is made relatively low, and the tension is made relatively high immediately after the wire has passed on each of the side former, so that the above-described method according to the first feature can be carried out suitably.
The foregoing and other objects, features, and advantages of the present invention will become more apparent by reference to the description of preferred embodiments given below in detail in connection with the accompanying drawings.